Drug-coated stents - used to prop open clogged coronary arteries - can continue to be used on Britain's state health service but only for certain high-risk patients, the country's health cost-effectiveness watchdog said.

New guidance from the National Institute for Health and Clinical Excellence (NICE) on Wednesday confirms a draft proposal first issued in February.

NICE caused a storm last August when it said drug-coated, or eluting, stents were not worth the extra cost compared with older bare metal ones.

The new guidance, however, says that they are suitable for patients who are at higher risk of needing further stents if a bare one were used instead.

NICE is recommending drug stents as a possible treatment when a coronary artery is less than 3mm in diameter, or the section of the artery to be treated is longer than 15mm. Such lesions are particularly tricky to treat.

Drug stents should also only be used if the price difference with bare metal ones is no more than 300 pounds, NICE added.

Drug-coated versions of stents - tiny, wire-mesh tubes that are inserted into arteries - are a multibillion-dollar global business for companies like Boston Scientific, Johnson & Johnson, Medtronic and Abbott Laboratories.

But their use has fallen sharply in the past two years on concerns they may sometimes cause blood clots.

Decisions by NICE, which assesses treatments for reimbursement on the state health service in England and Wales, are closely watched by other governments and insurers, particularly in Europe.